In a two-cycle gasoline engine or the like for such small operating machine as is mentioned above, exhaust gas is delivered to an exhaust muffler out of an exhaust port of a cylinder, is silenced there and is discharged out.
The above mentioned exhaust muffler is provided to silence and clean the exhaust gas. There have been already provided many products in which such sound absorbing member as a porous plate or glass wool is arranged and used within an exhaust muffler to silence the exhaust gas or various catalysts are used to clean the exhaust gas.
There have been defects that, when such sound absorbing member as glass wool or any catalyst is used as mentioned above, specifically in a small two-cycle gasoline engine, carbon and tar produced by the combustion of a lubricating oil mixed with fuel will be deposited further in the exhaust gas path, the weight of the exhaust muffler and the back pressure by the exhaust gas will increase, the interval of the maintenance of the exhaust muffler will become short and the effective life of the exhaust muffler will become very short.